cdhdr and cdpos object id and object class issue

Earlier i was fetching the zterm like this.

if sy-subrc = 0.

select kunnr

vkorg

zterm

from knvv

into table it_knvv

for all entries in it_knb1

where kunnr = it_knb1-kunnr.

if sy-subrc = 0.

sort it_knvv by kunnr.

endif.

endif.

read table it_tvko into wa_tvko with key bukrs = wa_knb1-bukrs.

CLEAR wa_knvv.

READ TABLE it_knvv INTO wa_knvv WITH KEY kunnr = wa_final-kunnr

vkorg = wa_tvko-vkorg.

IF sy-subrc = 0.

wa_final-zterm = wa_knvv-zterm.

ENDIF.

Now i want to have the new and old values of zterm.So need to use the cdhdr and cdpos.

so what will be the object id and object clas for the cdhdr table and cdpos,

kindly suggst.how to fetch the data from these tables.